Lukaku did not accept the bet, and Ibrahimovic joked that he would have become a better player had he done so.
The pair were forward colleagues for a season at Old Trafford.
“I will say this on Romelu,” Ibrahimovic told Gazzetta dello Sport. “Don’t expect good technique from Lukaku. His best strength is sheer power – if only he’d listened to me.
“At Manchester United, we made a bet: ‘I’ll give you £50 for every decent first touch you make’. He replied: ‘What do I win if I get them all right?’ I told him nothing, he would simply become a better player.
“For the record, he never accepted the bet! Perhaps he was afraid of losing...”
Lukaku has been criticised for his poor control in the past, particularly after joining Manchester United for £75 million in 2017.
He departed the club this summer, and has started well at Inter Milan, with three goals in his first seven league games,
Ibrahimovic, who scored 57 goals for Inter during a three season spell at the San Siro, thinks Lukaku will be a success at his former club.
“Joking aside, Lukaku has this mad hunger to prove himself to the world,” the Swedish striker said. “And I’m sure he will do well at Inter too.”
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